In News:

Seaweed farming has emerged as a potential Blue Carbon strategy, yet empirical estimates of carbon burial from such farms remain lacking in the literature.

What is Blue Carbon?

• Blue Carbon refers to organic carbon captured and stored by ocean-based vegetated ecosystems such as mangroves, saltmarshes, and seagrass meadows.
• The term “blue” highlights its association with aquatic ecosystems.
• Most blue carbon comes from carbon dioxide dissolved directly into the ocean. Smaller amounts are stored in:
  • Underwater sediments and soils
  • Coastal vegetation
  • Organic molecules (DNA, proteins, etc.)
  • Marine organisms (phytoplankton, whales, etc.)
• Despite covering just 2% of the ocean surface, these ecosystems account for 50% of total oceanic carbon absorption, making them vital in global climate mitigation efforts.

Seaweed Farming as a Blue Carbon Strategy

• Emerging Role: Seaweed cultivation has been identified as a potential Blue Carbon pathway, though empirical evidence of its carbon burial capacity has been limited until recently.
• Global Study: An analysis of 20 seaweed farms worldwide, aged between 2 and 300 years and ranging from 1 to 15,000 hectares, provides new insights.
• Findings:
  • Sediment organic carbon stocks increased with farm age, reaching 140 tC ha?¹ in the oldest farm.
  • Average burial rates: 1.87 ± 0.73 tCO?e ha?¹ yr?¹ in farm sediments, nearly double that of nearby reference sediments.
  • Excess CO?e burial attributable to seaweed farming: 1.06 ± 0.74 tCO?e ha?¹ yr?¹.
• Conclusion: Seaweed farms in depositional environments act as effective carbon sinks, with burial rates at the lower end of traditional Blue Carbon habitats but increasing significantly with farm maturity.

Significance

• Reinforces the role of marine ecosystems in carbon sequestration.
• Highlights seaweed farming as a scalable, nature-based climate solution alongside mangroves, saltmarshes, and seagrasses.
• Provides a scientific basis for integrating seaweed aquaculture into Blue Carbon policies and climate strategies.